scholarly journals Electrically Tunable Fresnel Lens in Twisted-Nematic Liquid Crystals Fabricated by a Sagnac Interferometer

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1448 ◽  
Author(s):  
Bing-Yau Huang ◽  
Tsung-Hsien Lin ◽  
Tian-Yi Jhuang ◽  
Chie-Tong Kuo
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Azo Dye ◽  
Focal Length ◽  
Fresnel Lens ◽  
Sagnac Interferometer ◽  
Alignment Effect ◽  
Twisted Nematic ◽  
Linearly Polarized ◽  
Photo Alignment

This paper presents an electrically tunable Fresnel lens in a twisted nematic liquid crystal cell fabricated by using a Sagnac interferometer. When the Fresnel-patterned green beam, formed by the Sagnac interferometer, is irradiated on the azo-dye doped liquid crystal mixture, the azo-dye molecules undergo trans–cis photoisomerization and then generate the photo-alignment effect in the bright (odd) zones. The director of the liquid crystal molecules in the odd zones reorients the direction perpendicular to the polarization direction of the linearly polarized green beam. The various structures of liquid crystals in the odd and even zones will result in a phase difference and thus, a Fresnel lens can be generated. The experimental results show that the proposed Fresnel lens has a high diffraction efficiency of 31.5% under an applied alternating-currents (AC) voltage. The focal length of the Fresnel lens can also be tuned by thermally erasing the photo-alignment effect of the azo dyes and rewriting by a different Fresnel-like pattern.

scholarly journals A Planar Fresnel Lens in Reflection Type Based on Azo-Dye-Doped Cholesteric Liquid Crystals Fabricated by Photo-Alignment

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2972
Author(s):  
Bing-Yau Huang ◽  
Ting-Hui Chen ◽  
Tzu-Yeh Chen ◽  
Jia-De Lin ◽  
Tsung-Hsien Lin ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Azo Dye ◽  
Focal Length ◽  
Incident Light ◽  
Polarization State ◽  
Fresnel Lens ◽  
Dye Molecules ◽  
Cholesteric Liquid Crystals ◽  
Crystal Film ◽  
Photo Alignment

This paper presents a focusing efficiency and focal length tunable planar Fresnel lens in reflection type based on azo-dye-doped cholesterol liquid crystal film. The Fresnel-like pattern of a pumping beam can be formed by a Sagnac interferometer. When the azo-dye molecules are irradiated by the pumping beam, the photoalignment effect will be induced in the bright (odd) zones due to the trans–cis photoisomerization of azo-dye molecules. Thus, the structures of cholesteric liquid crystals in the odd zones will reorient from the imperfectly planar textures to the perfectly planar textures. The different structures of cholesteric liquid crystals in two adjacent zones will give rise to phase difference for the reflected light and thus function as a Fresnel lens. The focusing efficiency of the proposed Fresnel lens can be controlled by the applied voltages and affected by the polarization state of incident light. Moreover, various focal lengths of the Fresnel lens can be achieved by rewriting a different center radius of the Fresnel-like pattern.

Photo-alignment of liquid crystals in micro capillaries with point-by-point irradiation

2014 ◽  
Vol 22 (3) ◽  
Author(s):  
A. Siarkowska ◽  
M. Jóźwik ◽  
S. Ertman ◽  
T. Woliński ◽  
V. Chigrinov
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Azo Dye ◽  
Laser Light ◽  
Alignment Method ◽  
Uv Laser ◽  
Orientation Control ◽  
Photo Alignment

AbstractA photo-alignment method for micro capillaries based on the SD-1 azo-dye is demonstrated. In this work a liquid-crystal molecules aligning layer is created by point-by-point irradiation of the azo-dye film by using an UV laser light. The method opens up new possibilities for an improved molecules’ orientation control in both glass- and polymer-based photonic liquid crystal fibres.

Optically controllable and focus-tunable Fresnel lens in azo-dye-doped liquid crystals using a Sagnac interferometer

2011 ◽  
Vol 36 (8) ◽  
pp. 1311 ◽  
Author(s):  
Hui-Chen Yeh ◽  
Yi-Chieh Kuo ◽  
Shih-Hung Lin ◽  
Jia-De Lin ◽  
Ting-Shan Mo ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Azo Dye ◽  
Fresnel Lens ◽  
Sagnac Interferometer

Photo-Alignment Effect in Liquid-Crystal Films Containing Nanoparticles and Azo-Dye

2010 ◽  
Vol 428-429 ◽  
pp. 276-279 ◽  
Author(s):  
Tsung Hsien Lin ◽  
Wen Zheng Chen
Keyword(s):  
Liquid Crystal ◽  
Azo Dye ◽  
Polyhedral Oligomeric Silsesquioxanes ◽  
Alignment Effect ◽  
Practical Applications ◽  
Liquid Crystal Films ◽  
Crystal Film ◽  
Crystal Films ◽  
Alignment Technique ◽  
Photo Alignment

This work reports the photo-alignment effect in a liquid-crystal film doped with nanoparticles and azo-dye. Vertical alignment induced by the nanoparticles polyhedral oligomeric silsesquioxanes (POSS) can be switched to homogeneous alignment by the absorption of photo-excited azo-dye. Both electro-optical and surface properties are analyzed to verify this effect. Using this photo-alignment technique in nanoparticle- and azo-dye-doped liquid crystal, the phase grating is also demonstrated. The diffraction efficiency is related to the polarization of the probe light and can be controlled by applying voltage. Both nanoparticle- and azo-dye-induced vertical and homogeneous alignments are non-contact aligning methods. Thus, the technique based on dopant-induced alignment has potential for practical applications.

P-118: Azo Dye, Liquid Crystals Polymer Composite Photo-Alignment Layer for Modern Liquid Crystal Displays

2016 ◽  
Vol 47 (1) ◽  
pp. 1566-1569 ◽  
Author(s):  
Cui-Ling Meng ◽  
Man-Chun Tseng ◽  
Chung-Yung Lee ◽  
Abhishek K. Srivastava ◽  
Vladimir G. Chigrinov ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Polymer Composite ◽  
Azo Dye ◽  
Liquid Crystal Displays ◽  
Alignment Layer ◽  
Photo Alignment

Effect of Photo-Isomerization of Azo Dyes on the Photonic Bandgap in Chiral Nematics

2011 ◽  
Vol 181-182 ◽  
pp. 257-260
Author(s):  
David Statman ◽  
Andrew Jockers ◽  
Daniel Brennan
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Azo Dyes ◽  
Azo Dye ◽  
Photonic Bandgap ◽  
Methyl Red ◽  
Central Wavelength ◽  
Chiral Nematic ◽  
Anchoring Energy ◽  
Pitch Length

Chiral nematic liquid crystals prepared with Grandjean texture demonstrate a photonic bandgap whose central wavelength is proportional to the pitch length, P, of the liquid crystal and whose width is given by (ne – no)P. We show that methyl red doped chiral nematics undergo a shift in the photonic bandgap upon photo-isomerization. This shift is a result of (1) photo-induced change in anchoring energy on the nematic surface, and (2) change in the natural pitch length from the photo-isomerization of the azo dye.

scholarly journals Electrically Controlled Diffraction Grating in Azo Dye-Doped Liquid Crystals

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1051 ◽  
Author(s):  
Chuen-Lin Tien ◽  
Rong-Ji Lin ◽  
Chi-Chung Kang ◽  
Bing-Yau Huang ◽  
Chie-Tong Kuo ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Electric Fields ◽  
Azo Dye ◽  
Nematic Liquid Crystals ◽  
Polarized Light ◽  
Dielectric Anisotropy ◽  
Linear Effect ◽  
Periodic Distribution ◽  
The Difference

This research applies the non-linear effect of azo dye-doped liquid crystal materials to develop a small, simple, and adjustable beam-splitting component with grating-like electrodes. Due to the dielectric anisotropy and optical birefringence of nematic liquid crystals, the director of the liquid crystal molecules can be reoriented by applying external electric fields, causing a periodic distribution of refractive indices and resulting in a diffraction phenomenon when a linearly polarized light is introduced. The study also discusses the difference in the refractive index (Δn), the concentration of azo dye, and the rising constant depending on the diffraction signals. The experimental results show that first-order diffraction efficiency can reach ~18% with 0.5 wt % azo dye (DR-1) doped in the nematic liquid crystals.

All-optical switchable holographic Fresnel lens based on azo-dye-doped polymer-dispersed liquid crystals

2011 ◽  
Vol 50 (22) ◽  
pp. 4295 ◽  
Author(s):  
Hossein Jashnsaz ◽  
Nahid Hosain Nataj ◽  
Ezeddin Mohajerani ◽  
Amir Khabbazi
Keyword(s):  
Liquid Crystals ◽  
Azo Dye ◽  
Fresnel Lens ◽  
Polymer Dispersed Liquid Crystals ◽  
All Optical ◽  
Polymer Dispersed ◽  
Doped Polymer
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